This invention relates to the art of reclosable bags of the kind provided with extruded resiliently flexible plastic profiled reclosable separable fastener means, and is more particularly concerned with a new and improved method of and means for making material for such bags, and material produced thereby.
The art of making reclosable bags equipped with extruded plastic profiled reclosable separable fastener means has seen a long period of development as reflected in numerous patent disclosures. It has been conventional practice to extrude plastic material in tubular or strip sheet or web form with the profiled separable fastener means coextruded along and parallel to the longitudinal formation axis of the web, that is, the direction in which the web is extruded. On the other hand, prefabricated separable fastener strip means have been secured to separately formed web but with the fastener strip means extending longitudinally parallel to the longitudinal formation axis of the web, that is, the length of the web as extruded or otherwise formed.
By way of example, U.S. Pat. No. Re. 29,043 is referred to as disclosing coextrusion of web and fastener means and forming the same into bag sections.
U.S. Pat. No. 3,948,705 exemplifies the technique of securing reclosable separable fastener strips to plastic film parallel to the longitudinal formation axis of the web by fusion or heat seal methods.
Attachment of separable fastener strips parallel to the longitudinal formation axis of the web by adhesive means is exemplified in U.S. Pat. Nos. 4,354,541 and 4,372,793.
U.S. Pat. No. 4,046,408 discloses separably interlockable fasteners along the edges of the plastic sheet material having generally arrow shaped profiles, the fasteners being either integrally extruded with flat sheets or tubes of plastic film, or supplied in the form of extruded strips attached to the web or film by heat sealing.
According to all of those prior patent disclosures, it is necessary to provide at least a pair of spaced longitudinally extending complementary profile fastener strips along the longitudinal extent or axis of the bag material web or film so that when the material is folded upon itself along one or more folds parallel to the separable fastener strips, the fastener profiles will be aligned with one another in interlockable relation and extend along the top or bag mouth edges of the bag sections into which the material is subdivided by sealing the same at spaced intervals across the length of the material to provide closed sides for the bag sections.
Where separate matching strips of the web or film material carrying the complementary profile fastener strips longitudinally along the longitudinal extent of the material are aligned in face-to-face relation to provide bag sidewalls, the same requirements must be met according to prior practice as described for the foldable material for fabricating the same into bag sections, except that all side and bottom edges of the bag walls must also be secured together in the completed bags.
Prior techniques do not necessarily limit the length of bags to be produced thereby, that is, the length from the bag top end to the bottom end of the bag, unless the bags are supplied for filling by the type of filling machines commonly referred to as form, fill and seal machines, such as exemplified in U.S. Pat. Nos. 3,789,888 and 4,355,494.
Where the fastener strip means are located longitudinally along the length of the bag making web material as shown in U.S. Pat. No. 4,355,494, the length of the bags that can be produced in the form, fill and seal machines is limited to the diameter of the filling nozzle about which the film or web material is progressively wrapped. Further, unless the fastener profiles are interlocked before the bag forming material is wrapped about the forming extent of the filling nozzle or at least before the usual longitudinal sealing of the joined longitudinal edges or margins of the bag forming material, there is a considerable problem with attaining interlockable registration of the fastener profiles.
According to a novel concept as disclosed in copending application of Paul B. Christoff and Steven Ausnit, Ser. No. 574,878 filed Jan. 30, 1984 (now U.S. Pat. No. 4,617,683) and assigned to the same assignee as the present application, there is provided a reclosable bag and a method of making the same, and method of and means for making material for such bags, wherein the extruded resiliently flexible plastic profiled reclosable fastener means is secured across the length of the bag making material web, instead of along the length of the web as effected according to prior practice. This has numerous advantages, as there pointed out, especially with respect to filling in a so-called vertical form, fill and seal machine.